A fan with copper winding in its motor consumes less power as compared to an otherwise similar fan having aluminium winding.Explain.

Explain the operation of motor used in fans.

In the tropical rainforest, the majority of trees have showy animal-pollinated flowers. In temperate forests the majority of trees are wind pollinated. Which factors best explain these contrasting patterns ? (i) Wind is rare in tropical forests. (ii) Because of high species diversity in the tropics, individuals of trees species are often widely separated making wind an inefficient means of pollen dispersal. (iii) More opportunities for coevolved mutualisms exist in tropical forests because of the high diversity of animal species. (iv) Trees in tropical forests are mostly evergreen and year-round leaf canopies impede pollen dispersal by wind. (v) Flowering in tropical forests occurs over a short period of time when wind is absent. (a) (i) , (ii) and (v) (b) (i),(iii) and (v) (c) (ii), (iii) and (iv) (d) (ii) and (iv)

A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?

A wind - powered generator converts wind energy into electric energy. Assume that the energy intercepted by its blades into electrical energy. For wind speed v, the electrical power output will be proportional to,

A copper wire having resistance 0.01 ohm in each metre is used to wind a 400 turn solenoid of radius 1.0 cm and length 20 cm. Find the emf of a battery which when connected across the solenoid will cause a magnetic field of (1.0 xx 10^-2) T near the centre of the solenoid.